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Subject: Re: [PATCH] [RFT] sh: mach-r2d: Handle virq offset in cascaded IRL
 demux
To:     John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Guenter Roeck <linux@roeck-us.net>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>
CC:     <linux-sh@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <2c99d5df41c40691f6c407b7b6a040d406bc81ac.1688901306.git.geert+renesas@glider.be>
 <d92853f1a37158d37fefcc84b59efae9b0fb903b.camel@physik.fu-berlin.de>
From:   Sergey Shtylyov <s.shtylyov@omp.ru>
Organization: Open Mobile Platform
Message-ID: <ef715abc-6be4-6473-15a1-05069b23bdc1@omp.ru>
Date:   Sun, 9 Jul 2023 15:50:48 +0300
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On 7/9/23 2:58 PM, John Paul Adrian Glaubitz wrote:
[...]
>> diff --git a/arch/sh/boards/mach-r2d/irq.c b/arch/sh/boards/mach-r2d/irq.c
>> index e34f81e9ae813b8d..c37b40398c5bc83e 100644
>> --- a/arch/sh/boards/mach-r2d/irq.c
>> +++ b/arch/sh/boards/mach-r2d/irq.c
>> @@ -117,10 +117,10 @@ static unsigned char irl2irq[R2D_NR_IRL];
>>  
>>  int rts7751r2d_irq_demux(int irq)
>>  {
>> -	if (irq >= R2D_NR_IRL || irq < 0 || !irl2irq[irq])
>> +	if (irq >= 16 + R2D_NR_IRL || irq < 16 || !irl2irq[irq - 16])
>>  		return irq;
>>  
>> -	return irl2irq[irq];
>> +	return irl2irq[irq - 16];
>>  }
>>  
>>  /*
> 
> Btw, I think this needs to be adjusted to test for "ret <= 0" since IRQs cannot
> be zero anymore, correct?
> 
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/mfd/sm501.c#n1389

   No, just ignore IRQ0 from now on, it can't be returned. Else you'd just complicate
your code as you'd have to add a separate check for IRQ0 in order to return -EINVAL
in this case (you can't return 0 from probe in case of ret == 0 as that would mean
successful probe when it's not).  My patch to platfrom_get_irq() ensures that IRQ0
check in its users is never needed, in order to avoid the (badly scaling) checks)...

> Adrian

MBR, Sergey